Five months for me, all but about ten from leaflets.
While I'm looking: now, 25 months later, I have cleaned at least once at 976 custopmers. A bundle of those have been one-offs, drifted away, died, been dropped, etc, but left with more than enough - so, in summary, I've gained 40 new customers every month since starting. The difference is that at the moment we've no advertising or leaflets going out but there's no let-up in the calls coming in.
Vin